The use of steam to aid in the harvesting of very dry crops has proven to be very effective. Presently, adjusting the steam application rate to effectively re-hydrate a particular crop during baling has been based more on the experience of the operator than based on science. Crop conditions, crop yield and ambient weather conditions are a few of the factors or variables which play a role in steam application/steam absorption. An accurate reliable feedback system is needed to inform the operator of what rate of steam application is needed.
Most current balers maintain constant bale density by maintaining a constant plunger force. Plunger force is maintained constant by changing the pressure the baling chamber bale chute applies to the bale as the bale is being formed. The amount of friction between the bale and the bale chute is a factor in the bale chute pressure needed to generate the desired plunger force. Since the crop's moisture content affects the amount of friction between the bale and the bale chute, bale chute pressure can be used as a rough indication of moisture content and, thus, can be used to determine the steam application rate. However, this relationship is different for different crop conditions, bale densities, crop types, ambient temperatures, etc. and is not a reliable method for determining the rate of steam application.
Present moisture sensors are inadequate for the purpose of determining proper steam application rates. These sensors have many shortcomings including:                1) the lack of accuracy needed to measure the small amount of moisture added to the crop by steaming;        2) errors due to the temperature shift the crop undergoes during steam application;        3) no compensation for the high amount of surface moisture present on the crop due to the steaming process; and        4) the fact that most moisture sensors are affected by density changes and lack compensation for the large variance in crop package density that steaming allows.        
The problem to be solved then is to find an accurate measure for determining the correct steam application rate for re-hydrating dry crop.